PHOENIX -- An already difficult second NFL season came to an end for Arizona's Matt Leinart on Tuesday when he was placed on injured reserve with a broken collarbone.

Kurt Warner, the 36-year-old quarterback who had shared duties with Leinart, moves into the starting job. The team signed Tim Rattay on Tuesday to be Warner's backup.

Leinart, a left-hander, fractured his left collarbone when he was sacked by Will Witherspoon in the second quarter of the Cardinals' 34-31 victory over the Rams in St. Louis on Sunday. He sat on the sideline in the second half with his arm in a sling.

Tough break for the Cards, but this is the sort of reason Warner was kept around in the first place. They won't hurt more than they usually do.